Dental self-etching primer

ABSTRACT

Bond strength of a composite resin, an adhesive resin cement or the like to dentin or enamel of tooth is remarkably improved by treating the dentin or the enamel with a self-etching primer agent comprising an aqueous solution of a methacrylic acid derivative such as N-methacryloylglycin, N-methacryloyl-3-aminopropionic acid, N-methacryloyl-4-aminobutyric acid, N-methacryloyl-5-aminovaleric acid, N-methacryloyl-6-aminocaproic acid, N-methacryloyl-2-aminomethylphosphonic acid, N-methacryloyl-3-aminoethyl-phosphonic acid and N-methacryloyl-4-aminopropylphosphonic acid.

FIELD OF THE INVENTION

The present invention relates to a self-etching primer agent for dentaltreatment. In more detail, the present invention relates to aself-etching primer agent for dental treatment to be used for surfacetreatment of dentin or enamel of tooth to which a composite resin isbonded with a bonding agent, or a metal or an orthodontic bracket or thelike is bonded with an adhesive resin cement, a dental kit for bonding adental materials to dentin or enamel of tooth comprising saidself-etching primer agent for dental treatment as a component reagentthereof, and a novel methacrylic acid derivative to be used for saidself-etching primer agent for dental treatment. In addition, the presentinvention relates to a method for surface treatment of dentin or enamelof tooth, and use of an aqueous solution of a methacrylic acidderivative for producing a surface treatment agent for dentin or enamelof tooth.

BACKGROUND OF THE INVENTION

Nowadays, in case of bonding a composite resin as a cavity fillingmaterial to dentin of tooth with a bonding agent or bonding a metal suchas an inlay and a crown to dentin of tooth with an adhesive resincement, after treating the surface of the dentin of tooth, usually sucha method is employed to adhere a bonding agent or an adhesive resincement to the dentin of tooth, and bond a composite resin through thebonding agent or bond a metal through the adhesive resin cement to thedentin of tooth. The surface treatment of dentin of tooth includesetching treatment and primer treatment. In etching treatment, a surfaceof dentin is made rugged due to decalcification by dissolving a smearlayer and hydroxylapatite of the dentin, followed by penetrating of abonding agent or an adhesive resin cement into the rugged surface andhardening thereof to enhance their mechanical holding strength andenable to adhere the dentin to the bonding agent or the adhesive resincement. Primer treatment modifies the dentin of tooth to a suitablestate for adhering the bonding agent or the adhesive resin cement.

Such a method for the surface treatment of dentin includes, forinstance, a method of etching treatment of dentin with ethylenediaminetetraacetic acid (EDTA) followed by primer treatment with a mixedaqueous solution of glutaraldehyde and 2-hydroxyethylmethacrylate (HEMA)(Munksgaard, E. C., et al., J. Dent. Res., 63(8), 1087-1089, 1984), amethod of etching treatment of dentin by deashing with an aqueoussolution of orthophosphoric acid, followed by primer treatment for acollagen layer of the dentin with an aqueous solution of HEMA after airdrying (Sugisaki, et al., Jpn. J. Conserv. Dent., 34(1), 228-265, 1991;Meerbeek, B. V., et al., J. Dent. Res. 72(2), 495-501, 1993; Pashley, D.H., et al., Quintessence Int. 24(9), 618-631, 1993), and the like.

In order to simplify the surface treatment of dentin, studies have beenprevalent on a self-etching primer agent with which both of etchingtreatment and primer-treatment are performed at the same time. Withregard to a self-etching primer agent, for instance, use ofN-acryloylaspartic acid (N-AAsp), a derivative of aspartic acid as oneof dicarboxylic acids, is proposed as a self-etching primer agent (Ito,et al., Dental Material and Apparatus, 15(4), 341-347, 1996; Ito et al.,Dental Material and Apparatus, 16(2), 155-159, 1997; Ito, et al., DentalMaterial and Apparatus, 16(1), 38-43, 1997). The N-AAsp is considered todecalcify the dentin as an acidic monomer and at the same time act onboth of an inorganic material and an organic material in dentin as afunctional monomer.

Lately, studies have been prevalent on a self-etching primer agentapplicable to both of dentin and enamel (Watanabe, Dental Material andApparatus, 11(6), 955-973, 1992; Fukushima, et al., Dental Material andApparatus, 11(4), 679-684, 1992). These self-etching primer agentscomprise an acid or an acidic monomer capable of decalcification and afunctional monomer to promote diffusion and penetration of a bondingagent. In addition, a mixed aqueous solution of N-methacryloylalanineand HEMA has been proposed as a self-etching primer agent for dentin andenamel (Takahashi, et al., Dental Material and Apparatus, 9(1), 65-73,1990). With regard to an action mechanism of the agent, it is consideredthat N-methacryloylalanine decalcifies hydroxyapatite as an acid to makea collagen fiber being exposed, on which HEMA acts as a primer.

On the other hand, it has been reported that a strong adhesion of acomposite resin to dentin can be obtained by treating the dentin etchedby an aqueous solution of phosphoric acid with an N-methacryloyl-ω-aminoacid such as N-methacryloylglycin, N-methacryloyl-4-aminobutyric acidand N-methacryloyl-6-aminocaproic acid as a primer agent (Nishiyama, etal., Dental Material and Apparatus, 13(1), 73-77, 1994; Nishiyama, etal., Dental Material and Apparatus, 17(2), 120-125, 1998). However, useof such an N-methacryloyl-ω-amino acid as a self-etching primer agenthas not been so far known.

DISCLOSURES OF THE INVENTION

Thus, an object of the present invention is to provide a self-etchingprimer agent for dentin or enamel of tooth using such anN-methacryloyl-ω-amino acid, an N-methacryloyl-aminoalkylphosphonicacid, an N-methacryloylaminoalkyl-sulfonic acid or the like, a dentalkit for bonding a dental material to dentin or enamel of toothcomprising said self-etching primer agent as a component reagent and anovel methacrylic acid derivative to be used for said self-etchingprimer agent.

After an intensive study to obtain a superior self-etching primer agentfor dentin or enamel of tooth, the present inventor has found thataqueous solutions of N-methacryloyl-ω-amino acid such asN-methacryloylglycin and N-methacryloyl-5-aminovaleric acid as well asN-methacryloyl-aminoalkylphosphonic acid,N-methacryloylaminoalkyl-sulfonic acid and the like are exceedinglysuperior as a self-etching primer agent for dentin or enamel indecalcifying effect for hydroxyapatite of the dentin and the enamel andalso in priming effect for an exposed collagen fiber of the dentin andthe enamel by decalcification, as well as in much improved bond strengthof a bonding agent or an adhesive resin cement to the dentin and theenamel, and accomplished the present invention.

Namely, an aspect of the present invention is a self-etching primeragent for dental treatment to be used for surface treatment of dentin orenamel of tooth, comprising an aqueous solution of a methacrylic acidderivative represented by the formula I below:

(wherein, n is an integer of 1 to 7; X is —COOH, —PO(OH)₂ or —SO₂OH).

Further, another aspect of the present invention is a dental kit forbonding a dental material to dentin or enamel of tooth, comprising theabove self-etching primer agent for dental treatment as a componentreagent thereof.

Still further, another aspect of the present invention is a methacrylicacid derivative represented by the formula I, where X is —PO(OH)₂ or—SO₂OH.

Still further, another aspect of the present invention is a method forsurface treatment of dentin or enamel of tooth, comprising applying aself-etching primer agent for dental treatment comprising an aqueoussolution of a methacrylic acid derivative represented by the formula I,to the surface of the dentin or the enamel of tooth.

Still further, another aspect of the present invention is use of anaqueous solution of a methacrylic acid derivative represented by theformula I for producing a surface treatment agent for dentin or enamelof tooth.

BEST MODE FOR CARRYING OUT THE INVENTION

The self-etching primer agent of the present invention is used forsurface treatment of dentin or enamel of tooth in case of bonding acomposite resin to dentin or enamel with a bonding agent or in case ofbonding a metal or an orthodontic bracket to dentin or enamel of toothwith an adhesive resin cement, and has both functions of an etchingagent and a primer agent. The self-etching primer agent of the presentinvention comprises an aqueous solution of a methacrylic acid derivativerepresented by the above formula I.

Such a methacrylic acid derivative includes N-methacryloyl-ω-amino acidssuch as N-methacryloylglycin, N-methacryloyl-3-aminopropionic acid(N-methacryloyl-β-alanine), N-methacryloyl-4-aminobutyric acid,N-methacryloyl-5-aminovaleric acid and N-methacryloyl-6-aminocaproicacid; N-methacryloylaminoalkylphosphonic acids such asN-methacryloyl-2-aminomethylphosphonic acid,N-methacryloyl-3-aminoethylphosphonic acid,N-methacryloyl-4-aminopropyl-phosphonic acid,N-methacryloyl-5-aminobutylphosphonic acid andN-methacryloyl-6-aminopentylphosphonic acid; andN-methacryloylaminoalkylsulfonic acids such asN-methacryloyl-3-aminoethylsulfonic acid,N-methacryloyl-4-aminopropyl-sulfonic acid,N-methacryloyl-5-aminobutylsulfonic acid andN-methacryloyl-6-aminopentylsulfonic acid. Among these,N-methacryloylglycin, N-methacryloyl-3-aminopropionic acid,N-methacryloyl-4-aminobutyric acid, N-methacryloyl-5-aminovaleric acid,N-methacryloyl-6-aminocaproic acid,N-methacryloyl-2-aminomethylphosphonic acid,N-methacryloyl-3-aminoethylphosphonic acid andN-methacryloyl-4-aminopropylphosphonic acid are preferable.

Each of the above N-methacryloyl-ω-amino acids,N-methacryloylaminoalkylphosphonic acids andN-methacryloyl-aminoalkylsulfonic acids may be used alone, or theN-methacryloyl-ω-amino acid may be used in combination with anN-methacryloylaminoalkylphosphonic acid, anN-methacryloylaminoalkylsulfonic acid or a mixture thereof. Saidcombined use is preferable because the priming effect is particularlyimproved in addition to the decalcification effect.

Such a methacrylic acid derivative can be synthesized as follows. TheN-methacryloyl-ω-amino acid can be obtained by a condensation reactionbetween a methacrylic halide such as methacrylic chloride and acorresponding ω-amino acid (Nishiyama, et al., Dental Material andApparatus, 13(1), 73-77, 1994). The N-methacryloylaminoalkylphosphonicacid or the N-methacryloylaminoalkylsulfonic acid can be obtained by acondensation reaction between a methacrylic halide and a correspondingaminoalkylphosphonic acid or a corresponding aminoalkylsulfonic acid,respectively. These N-methacryloyl-aminoalkylphosphonic acid andN-methacryloylaminoalkyl-sulfonic acid are novel compounds.

In the present invention, an aqueous solution of the above methacrylicacid derivative is used as a self-etching primer agent. A suitableconcentration of the aqueous solution is usually 10⁻⁵ to 10% by mole,preferably 10⁻³ to 8% by mole. The above methacrylic acid derivative isvery suitable for a self-etching primer agent because of its highsolubility in water. Further, the aqueous solution of a methacrylic acidderivative may be added with ethanol if necessary. In this case, anaqueous solution of ethanol with, for instance, a concentration of 40%or less may be prepared as a self-etching primer agent. The self-etchingprimer agent of the present invention may be properly added, ifnecessary, with a polyfunctional monomer or an alcohol, both of whichare ordinary additives.

The self-etching primer agent of the present invention may be used forsurface treatment of dentin or enamel of tooth usually by applying theaqueous solution thereof to dentin or enamel of tooth after polishingthem and reacting for about 10 to 50 seconds, followed by air drying.After the surface treatment, a bonding agent may be applied and then acomposite resin may be adhered. A metal or an orthodontic bracket mayalso be bonded to the dentin or the enamel using an adhesive resincement. The surface treatment of the dentin or the enamel with theself-etching primer agent of the present invention enables the compositeresin, metal and the like to be adhered very firmly.

Each of a bonding agent, a composite resin, an adhesive resin cement, ametal and an orthodontic bracket is not particularly limited, but anordinary product may be used in a usual manner. An example of thebonding agent includes a bonding agent comprising10-methacryloyloxy-decamethylenephosphoric acid (MDP) and apolyfunctional monomer; an example of the adhesive resin cement includesa 4-META/MMA-TBB resin obtained by polymerizing methylmethacrylate (MMA)dissolving 4-methacryloxyethyl-trimellitic anhydride (4-META) withpartially oxidized tri-n-butylborane (TBB) in the presence ofpolymethylmethacrylate (PMMA); and an example of the composite resinincludes a composite resin comprising a polyfunctional monomer andsilica. With regard to the metal, the metal for dental treatment to beused for an inlay or a crown includes a gold alloy for casting, agold-silver-palladium alloy for casting and a silver alloy for casting.The orthodontic bracket includes the one usually used.

The self-etching primer agent of the present invention can constitute adental kit to bond dental materials such as a composite resin, a metaland an orthodontic bracket to tooth, together with a bonding agent, anadhesive resin cement and the like, or together with reagents to preparethem.

The present invention will be described in more detail by Exampleshereinbelow, but should not be limited by these Examples.

EXAMPLE 1

Preparation of a Self-Etching Primer Agent

As a self-etching primer agent, 5% by mole of N-methacryloylglycin(NMGly) or N-methacryloyl-5-aminovaleric acid (NMVa) was dissolved indistilled water, to prepare an NMGly solution or an NMVa solution,respectively.

EXAMPLE 2

Measurement of Tensile Bond Strength of a Composite Resin to Dentin andEnamel

(1) Method of Adhesion Test

Fresh dentin was exposed by smoothly polishing a freshly extractedbovine anterior tooth under sprinkled water with silicon carbide paper(#400 and #600). A polyethylene ring (inside diameter: 3.8 mm, height:2.0 mm) was temporarily mounted onto the polished surface of dentin, ofwhich an inner surface was treated with the solution of NMGly or NMVafor 30 seconds and dried with air for 10 seconds. Clearfil Megabond(made by KURARAY CO., LTD.) was applied as a bonding agent to thesurface, then air-dried (three-way syringe, mild, made by MORITA Corp.)and exposed to light (Quicklight, UL1, made by MORITA Co., Ltd.) for 10seconds. Immediately after the above procedure, Clearfil AP-X (made byKURARAY CO., LTD.) was filled as a composite resin and exposed to lightfor 30 seconds to prepare a specimen. The specimen was left for standingat room temperature for 5 minutes and then dipped into water of 37° C.

After dipping for 24 hours, the specimen was taken out of water andsubjected to measurement of tensile bond strength of the resin to thedentin. In more detail, after fixing an attachment made of brass to anupper part of the composite resin with a cyanoacrylate adhesive, tensilebond strength was measured under a crosshead speed of 2 mm/min using auniversal testing machine (DCS-2000 made by SHIMADZU Corp.) equippedwith attachments for bond strength measurement. Ten specimens wereprepared for each condition.

In addition, a polished surface of fresh bovine enamel was treated withan NMGly or NMVa solution according to the similar method to the above,to measure bond strength of the composite resin to the enamel.

(2) Results

The bond strengths of the resin to crown dentins and enamels treatedwith the NMGly or NMVa solution are shown in Table 1.

TABLE 1 Bond strengths of the resin to the crown dentins and the enamelstreated with the self-etching primer agents Tensile Bond Strength (MPa)Crown Dentin SD Enamel SD NMGly 27.9 5.1 12.3 4.5 NMVa 15.7 8.7 6.4 2.6

The bond strengths of the resin to crown dentin was 27.9 MPa for theNMGly solution treatment and 15.7 MPa for the NMVa solution treatment,both showing high values.

On the other hand, the bond strength of the resin to enamel was 12.3 MPafor the NMGly solution treatment, which was higher than the bondstrength of 6.4 MPa for the NMVa solution treatment.

From the above results, it was found that the NMGly solution gave ahigher bond strength than the NMVa solution.

EXAMPLE 3

Synthesis of N-methacryloylalkylphosphonic acid

(1) Synthesis Method

In a reactor equipped with an agitator, 15 ml of water and 0.16 mol ofsodium hydroxide were added. Then 0.0045 mol of aminoethylphosphonicacid, aminoethylphosphonic acid or aminopropylphosphonic acid (made byTokyo Kasei Kogyo Co., Ltd.) was dissolved therein, and the amino groupof aminomethylphosphonic acid, aminoethylphosphonic acid oraminopropylphosphonic acid was condensed with methacrylic chloride bydropping 0.045 mol of methacrylic chloride to the above solution whilethe reactor was cooled with ice. After completion of the reaction,hydrogen chloride gas was introduced while the reactor was cooled byadding methanol (made by Wako Pure Chemical Industries Ltd.) to adjustpH of the reaction layer at 0.4 or less. After separating depositedsodium chloride by filtration, the solution was dried by addinganhydrous sodium sulfate. After filtration, the solvent was distilledoff under a reduced pressure. The residue was added with ethyl acetateand ethanol to crystallize N-methacryloyl-2-aminomethylphosphonic acid(NMMP), N-methacryloyl-3-aminoethylphosphonic acid (NMEP) orN-methacryloyl-4-aminopropylphosphonic acid (NMPP) followed by isolationand purification.

(2) Results

The NMR data of the compounds obtained are shown in Table 2 to Table 4.

TABLE 2 Chemical shifts of the ¹³C NMR peaks assigned to NMMP CH₂═ >C<—CH₃ —CO—NH— α-CH₂— 121.65 139.10 17.92 171.80 38.19 35.98

TABLE 3 Chemical shifts of the ¹³C NMR peaks assigned to NMEP CH₂═ >C<—CH₃ —CO—NH— β-CH₂— α-CH₂— 121.266 139.45 18.56 170.27 34.61 28.36 26.36

TABLE 4 Chemical shifts of the ¹³C NMR peaks assigned to NMPP CH₂═ >C<—CH₃ —CO—NH— γ-CH₂— β-CH₂— α-CH₂— 121.25 139.29 121.24 172.07 40.3122.41 23.14 40.04 22.41

EXAMPLE 4

Synthesis of N-methacryloyl-3-aminoethylsulfonic acid

(1) Synthesis Method

In a reactor equipped with an agitator, 15 ml of water and 0.16 mol ofsodium hydroxide were added. Then 0.0045 mol of aminoethylsulfonic acid(made by Tokyo Kasei Kogyou Co., Ltd.) was dissolved therein, and theamino group of aminoethylsulfonic acid was condensed with methacrylicchloride by dropping 0.0045 mol of methacrylic chloride to the abovesolution while the reactor was cooled with ice. After completion of thereaction, hydrogen chloride gas was introduced while the reactor wascooled by adding methanol (made by Wako Pure Chemical Industries Ltd.)to adjust pH of the reaction layer at 0.4 or less. The solvent wasdistilled off under a reduced pressure. The residue was added with ethylacetate and ethanol to crystallize N-methacryloyl-3-aminoethylsulfonicacid, followed by isolation and purification.

(2) Results

The NMR data of the compound obtained are shown in Table 5.

TABLE 5 Chemical shifts of the ¹³C NMR peaks assigned toN-methacryloyl-3-aminoethylsulfonic acid CH₂═ >C< —CH₃ —CO—NH— β-CH₂—α-CH₂— 121.72 139.10 18.40 170.26 50.33 36.35

EXAMPLE 5

Measurement of Tensile Bond Strength of the Composite Resin to Dentinand Enamel

(1) An aqueous solution of 5% by mole of N-methacryloyl-3-aminopropionicacid (N-methacryloyl-β-alanine) (NMβAla) was prepared similarly as inExample 1. In order to examine performances of the above aqueoussolution of NMβAla as well as the aqueous solutions of NMGly and NMVaprepared again in Example 1 as self-etching primer agents, bondstrengths of the resin to the crown dentins and the enamels treated withthese aqueous solutions were measured similarly as in Example 2. Theresults obtained are shown in Table 6.

TABLE 6 Bond strengths of the resin to the crown dentins and the enamelstreated with the aqueous solutions of NMGly, NmβAla and NMVa TensileBond Strength (MPa) Crown Dentin SD Enamel SG NMGly 23.6 5.1 16.0 3.3NMβAla 24.0 3.9 2.9 1.7 NMVa 21.2 4.8 15.0 3.6

As apparent from the results in Table 6, the aqueous solutions ofNMβAla, NMGly and NMVa serving as self-etching primer agents improvedthe bond strength of the resin to crown dentin and enamel.

(2) Each of 0, 0.35, 0.7 and 1.4 mmol ofN-methacryloyl-3-aminoethylphosphonic acid (NMEP) synthesized in Example3 was added to the 5% by mole aqueous solution of NMGly prepared inExample 1, to prepare self-etching primer agents of aqueous solutions ofNMGly-NMEP. Bond strengths of the resin to the dentins and the enamelstreated with these aqueous solutions were measured. The results obtainedare shown in Table 7.

TABLE 7 Bond strengths of the resin to the crown dentin and the enameltreated with the aqueous solutions of NMGly-NMEP Amount of Tensile BondStrength (MPa) NMEP Added Crown Dentin SD Enamel SD   0 mmol 23.6 5.116.0 3.3 0.35 mmol 24.7 5.2 15.8 4.2  0.7 mmol 22.2 5.2 21.9 4.9  1.4mmol 14.1 4.9 23.8 5.5

As apparent from the results in Table 7, the addition of NMEP to the 5%by mole aqueous solution of NMGly particularly improved bond strength ofthe resin to enamel. Judging from the bond strength of the resin todentin and enamel, an optimum amount of NMEP to be added is estimated tobe about 7 mmol.

(3) Similarly, each of 0, 0.35, 0.7 and 1.4 mmol ofN-methacryloylethylsulfonic acid (NMES) synthesized in Example 4 wasadded to the 5% by mole aqueous solution of NMGly, to prepareself-etching primer agents of aqueous solutions of NMGly-NMES. Bondstrengths of the resin to the dentins and the enamels treated with theseaqueous solutions were measured. The results obtained are shown in Table8.

TABLE 8 Bond strengths of the resin to the crown dentins and the enamelstreated with the aqueous solutions of NMGly-NMES Amount of Tensile BondStrength (MPa) NMES Added Crown Dentin SD Enamel SD   0 mmol 23.6 5.116.0 3.3 0.35 mmol 12.5 5.3 14.9 2.2  0.7 mmol 14.3 5.2 14.1 4.9  1.4mmol 9.5 3.5 11.9 5.0

As apparent from the results in Table 8, the addition of NMES to theaqueous solutions of NMGly lowered bond strength of the resin to dentinand enamel.

(4) Self-etching primer agents were prepared by adding 0.7 mmol each ofN-methacryloyl-2-aminomethylphosphonic acid (NMMP),N-methacryloyl-3-aminoethylphosphonic acid (NMEP) andN-methacryloyl-4-aminopropylphosphonic acid (NMPP) synthesized inExample 3 to the 5% by mole aqueous solution of NMGly. Bond strengths ofthe resin to the dentins and the enamels treated with these aqueoussolutions were measured. The results obtained are shown in Table 9.

TABLE 9 Bond strengths of the resin to the crown dentins and the enamelstreated with the aqueous solutions of NMGly added with each of NMMP,NMEP and NMPP Tensile Bond Strength (MPa) Crown Dentin SD Enamel SD NMMP21.9 5.1 18.0 5.7 NMEP 22.2 5.2 21.9 4.9 NMPP 21.0 6.2 24.4 5.2

As apparent from the results in Table 9, the bond strength of the resinto enamel was improved more as a chain length of methylene group becamelonger. The bond strength to dentin remained almost constant.

INDUSTRIAL APPLICABILITY

As described above in detail, bond strength of a composite resin, anadhesive resin cement or the like to dentin or enamel of tooth isremarkably improved when the dentin or the enamel is treated with theself-etching primer agent of the present invention comprising an aqueoussolution of a methacrylic acid derivative such as N-methacryloylglycin,N-methacryloyl-3-aminopropionic acid, N-methacryloyl-4-aminobutyricacid, N-methacryloyl-5-aminovaleric acid, N-methacryloyl-6-aminocaproicacid, N-methacryloyl-2-aminomethylphosphonic acid,N-methacryloyl-3-aminoethyl-phosphonic acid andN-methacryloyl-4-aminopropylphosphonic acid prior to bonding of thecomposite resin, the adhesive resin cement or the like. Consequently,the self-etching primer agent of the present invention is exceedinglysuperior. Particularly, the self-etching primer agent of the presentinvention is exceedingly superior as an agent for the treatment ofdental diseases such as a root caries, a cervical caries and a directpulp capping where the bond strength of a composite resin or an adhesiveresin cement is crucial.

1. A method for etching and priming dentin or enamel of tooth,consisting of a step of: applying a self-etching primer agent for dentaltreatment consisting of an aqueous solution of (1) at least oneingredient selected from the group consisting ofN-methacryloyl-2-aminomethylphosphonic acid,N-methacryloyl-3-aminoethylphosphonic acid,N-methacryloyl-4-aminopropylphosphonic acid and mixtures thereof; and(2) N-methacryloylglycin, and (3) optionally ethanol in an amount up to40% by weight and (4) optionally a polyfunctional monomer or alcohol, tothe surface of an unetched dentin or an unetched enamel of a tooth so asto perform both of etching and primer treatments of the unetched dentinor the unetched enamel.
 2. The method according to claim 1, wherein aconcentration of (1) and (2) in the aqueous solution is 10⁻⁵ to 10% bymole.
 3. The method according to claim 2, wherein said concentration is10⁻³ to 8% by mole.
 4. The method according to claim 1 or 2, whereinsaid aqueous solution does not contain said (3) optional ethanol.
 5. Themethod according to claim 1 or 2, wherein said aqueous solution does notcontain said (4) optional polyfunctional monomer or alcohol.
 6. Themethod according to claim 4, wherein said aqueous solution does notcontain said (4) polyfunctional monomer or alcohol.